Japanese Patent Application No. 2008-508693 (WO2006/013396) discloses an apparatus that measures physical phenomena caused by the difference in ion mobility between substances. Such publication describes in particular an ion mobility spectrometer with an ion filter in the form of at least one ion channel that includes a plurality of electrodes. With this ion mobility spectrometer, it is possible for the filler to selectively input ion types according to the potential applied to the conductive layer that changes over time. Such potential has a drive electric field component and a transverse electric field component, and in a preferred embodiment, the respective electrodes contribute to the generation of both the drive electric field component and the transverse electric field component. Such device can be used even without a drift gas flow. In addition, such publication discloses a micromachining technology for manufacturing a microscale spectrometer for the various applications of a spectrometer.
FAIMS (Field Asymmetric waveform Ion Mobility Spectrometry or DIMS (Differential Ion Mobility Spectrometry)) is known as an example of a technology that measures ion mobility. With FAIMS technology, the chemical substances to be measured are compounds, compositions, molecules and other products that are capable of being ionized, and by using the property whereby ion mobility is unique for each chemical substance, a differential voltage (or “DV”, “Dispersion Voltage”, “Vd voltage”, “electric field voltage”, “AC voltage”, hereinafter simply “Vf”) and a compensation voltage (or “CV”, “compensation voltage”, “DC voltage”, hereinafter simply “Vc”) are applied while causing movement within a buffer gas. If Vf and Vc are appropriately controlled, the ionized chemical substance that is the detection target will reach a detector and be detected as a current value.
Accordingly, to use a sensor (ion mobility sensor) that measures ion mobility, it is important to supply chemical substances to be analyzed to the ion mobility sensor under appropriate conditions. This is also the same for other gas analyzing sensors.
One of aspects of the present invention is a gas sampling apparatus including: an air supplying unit that forms an air curtain to form a space that covers a region to which an object to be monitored is included and which is separated from the outside environment; a sampling unit that samples gas inside the separated space; and a diffusion gas supplying unit that supplies, into the separated space, an amount of diffusion gas that is at least equal to a sampled amount of the sampling unit. The sampling unit includes a plurality of sampling nozzles disposed at three-dimensionally different positions inside the separated space.
This gas sampling apparatus uses the sampling unit to sample gas including a chemical substance (target substance) released from the object by the diffusion gas. When doing so, by disposing the plurality of sampling nozzles at three-dimensionally different positions inside the separated space, it is possible to increase the probability of it being possible to sample gas including the target substance, even when the target substance released into the separated space by the diffusion gas is localized somewhere. By such arrangement, it may become possible to sample gas including a high concentration of the target substance, it will be possible to increase the detection precision and reduce the time required for detection.
It is desirable for the gas sampling apparatus to include a first driving unit that moves each of the plurality of sampling nozzles inside the separated space randomly or in accordance with a predetermined algorithm. It is also desirable for the gas sampling apparatus to include a first flowrate control unit that controls a sampled amount of each of the plurality of sampling nozzles randomly or in accordance with a predetermined algorithm. By doing so, it is possible to change the respective sampling conditions of the plurality of sampling nozzles.
It is desirable for the air supplying unit to include an air outlet that forms the separated space above a conveyor that conveys the object, and for the diffusion gas supplying unit to include a diffusion gas outlet that supplies the diffusion gas into the separated space from below the conveyor or along a conveying surface of the conveyor. It becomes easier for constituents released from a target substance included in the object, such as constituents/substances released from foreign materials or abnormalities), to reach the sampling nozzles in a short time. It is also desirable for the gas sampling apparatus to further include a temperature control unit that directly or indirectly heats the object inside the separated space. By heating the object, it is possible to promote releasing of the constituents of the target substance included in the object.
Another aspect of the present invention is a monitoring apparatus including the gas sampling apparatus described above, a sensor that detects at least one chemical substance included in the gas sampled by the sampling unit, and a piping system that connects the gas sampling apparatus and the sensor. It is desirable for the monitoring apparatus to include a heater unit that heats the piping system, which makes it possible to suppress the influence of pollution of the piping system.
It is desirable for the monitoring apparatus to further include a mixer unit that supplies a mixed gas produced by mixing the gas sampled by the sampling unit and a carrier gas to the sensor and also desirable to further include a concentration control unit that controls concentration by feeding back some of the mixed gas as the carrier gas. This makes it possible to easily concentrate the constituents to be detected by the sensor.
It is also desirable for the monitoring apparatus to further include a first feedback control unit that changes respective positions or movements of the plurality of sampling nozzles or a second feedback control unit that changes respective sampled amounts of the plurality of sampling nozzles according to the detection result of the sensor. It is possible to automatically select sampling conditions where the detection sensitivity of the sensor is high and to automatically set the selected sampling conditions.
Although the sensor may be a mass spectrometer, gas chromatography, or the like, an ion mobility sensor that is capable of detecting substances (molecules) in air in real time is preferable.
Yet another aspect of the present invention is a control method of a monitoring apparatus that investigates the state of an object, as examples, whether foreign matter is included in the object, the state of packaging, and the presence/absence of damage. The monitoring apparatus includes: a sampling unit that samples gas inside a space that is separated from the outside environment by an air curtain that covers the object; and a sensor that detects at least one chemical substance included in the gas sampled by the sampling unit, and the sampling unit includes a plurality of sampling nozzles disposed at different positions inside the separated space. The control method includes changing sampling conditions including at least one of a sampled amount, position, and movement of each of the plurality of sampling nozzles.
Changing the sampling conditions may include changing sampling conditions of the plurality of sampling nozzles randomly or in accordance with a predetermined algorithm. Also, changing the sampling conditions may include changing the sampling conditions of the plurality of sampling nozzles in accordance with a detection result of the sensor.